Owing to the recent fuel embargos and shortages, the use of wood stoves for heating has grown in the United States. Many modern stoves limit the amount of air to conserve fuel. The result is incomplete combustion and increased incidence of air pollution.
When wood completely burns, the normal result is water, carbon dioxide and a small amount of particulate matter. If the amount of oxygen is limited, for example if there is a smoldering fire in an airtight stove, combustion is incomplete. Incomplete combustion results in water, carbon monoxide, carbon (soot), hydrocarbons (creosote), and similar products. Several of these products are serious pollutants and have led to legal limitations on wood stove use in some communities. In addition, creosote condenses in cool portions of stove pipes and becomes a fire hazard. Finally, if combustion is incomplete, burning of the fuel produces fewer calories than complete combustion resulting in lower efficiency.
Due to the above problems, there have been many attempts to provide more complete combustion. The simplest is to provide adequate oxygen for combustion. While this method is simple in theory, in practice it is difficult to accomplish without constant monitoring of the stove and type of fuel. A second method proposed is injection of air into the combustion chamber of the flue to cause additional combustion. A problem that arises with this method is that while there is sufficient oxygen to burn the combustion products, there is insufficient heat to allow proper ignition. For this and similar reasons, addition of air is only partially successful. It has been proposed to add a catalytic converter to the stove or flue to reduce the temperature of ignition. The catalysts proposed are generally metals or metal coating on ceramic. Such catalysts are prone to poisoning and are relatively expensive. In addition, most designs create excessive back pressure which can fill the room in which the device is located with smoke. Accordingly, a need has arisen for an inexpensive reliable device which provides complete combustion in wood stoves.